Esters of polyunsaturated fatty acids can be produced both by chemical and by enzymatic methods. Chemical syntheses have the disadvantage that very high temperatures generally have to be used and large quantities of basic catalysts are required so that secondary products and unwanted isomerizations occur to a fairly significant extent. One way of reducing the reaction temperature in the chemical synthesis of glycerol esters of polyunsaturated fatty acids was disclosed in European patent application EP 1 354 934 A1. By using a mixed catalyst of a salt of a weak acid and a strong base together with the soap of an organic C2-26 acid, the reaction temperature was reduced to below 175° C. and preferably to 100-140° C. However, enzyme-catalyzed reactions with lipases still generally take place under milder conditions and give high-purity end products.
Thus, European patent EP 0 950 410 A1 and International patent WO 0 178 531 describe syntheses in which glycerol and free conjugated linoleic acid (CLA) are reacted with immobilized lipase at 65° C. in a vacuum of 0.01 to 0.5 torr to form CLA triglycerides. Similarly, according to European patent application EP 1174416 A1, glycerol and free CLA are reacted with lipase under reduced pressure at 70° C.
European patent application EP 1 322 776 A1 describes a lipase-catalyzed method for the production of triglycerides of polyunsaturated conjugated fatty acids from alkyl esters of the unsaturated fatty acids and glycerol which removes the alcohol formed from the reaction under reduced pressure. In addition, International patent application WO 9116443 A1 describes the esterification of glycerol and free polyunsaturated fatty acids or alkyl esters thereof to form the corresponding triglycerides by removing the water of reaction or the alcohol formed under reduced pressure.
However, enzymatic syntheses often have the disadvantage that the reactions are relatively slow.
Accordingly, the problem addressed by the invention was to improve the profitability of enzymatic processes for the production of triglycerides containing polyunsaturated fatty acids.